Función renal basal en pediatría: correlación de métodos que dependen de la recogida de orina de 24h con otros más sencillos que no requieren orina minutada / Basal renal function in paediatric patients: correlation of methods that depend on a 24 h urine collection with simpler methods that do not require a timed urine

INTRODUCCIÓN: En la práctica diaria es necesario disponer de métodos rápidos, sencillos y accesibles para valorar adecuadamente la función renal. Los objetivos fueron: 1) Cuantificar la relación y concordancia de la tasa de filtración glomerular (FG) calculada mediante el aclaramiento de creatinina en orina de 24 h (CCr) y la fórmula de Schwartz (FS) original y la FS modificada. 2) Relacionar la eliminación urinaria de sustancias que dependen del volumen de orina expulsada en una unidad de tiempo con otros parámetros que se calculan midiendo la concentración de estas sustancias en sangre y en orina. MATERIAL Y MÉTODOS: El estudio incluyó 401 niños sanos de 3-14 años (187 hombres y 214 mujeres). El análisis entre las variables se realizó mediante el coeficiente de correlación de Pearson y el coeficiente de concordancia intraclase (CCI) tipo consistencia. RESULTADOS: La correlación entre los valores de CCr y FS original (medición de creatinina no estandarizada) fue r = 0,58 (p < 0,001) y la concordancia, CCI = 0,74. La correlación entre las cifras de CCr y FS modificada (medición de creatinina estandarizada) fue r = 0,68 (p < 0,001) y la concordancia, CCI = 0,78. Existía una correlación muy significativa entre la eliminación de sodio en orina de 24 h (mEq/kg/24 h) y la excreción-fraccional-Na (EFNa): r = 0,8 (p < 0,001).También entre la eliminación de potasio en 24 h (mEq/kg/24 h) y EFK: r = 0,78 (p < 0,001). Entre la proteinuria (mg/m2/h) y el cociente proteína/creatinina urinario: r = 0,85 (p < 0,001). Y entre el volumen urinario (ml/min/1,73 m2) y el volumen % FG: r = 0,88 (p < 0,001). CONCLUSIONES: Estas ecuaciones proporcionan una valiosa información del estado de la función renal basal sin tener que recurrir a la orina minutada

INTRODUCTION: In daily clinical practice a quick, easy and accessible method is needed to adequately assess renal function. The objectives of this study were: 1. To quantify the relationship and concordance of the glomerular filtration rate (GF) calculated by the clearance of creatinine in 24 h urine (CCr) and the original and modified Schwartz equation (SE); and 2. To correlate urine elimination of substances that depends on the volume of excreted urine in a unit of time with other parameters that are calculated measuring the concentration of these substances in blood and urine. MATERIAL AND METHODS: The study included 401 healthy children with ages between 3 to 14 years (187 male and 214 female). The analysis between the variables was carried out using Pearson's correlation coefficient and the intraclass correlation coefficient (ICC). RESULTS: The correlation between values of CCr and the original SE (non-standardised creatinine measurement) was r = 0.58 (P < 0.001) and the concordance, ICC = 0.74. The correlation between CCr values and the modified SE (standardised creatinine measurement) was r = 0.68 (P < .001), and the concordance ICC = 0.78. There was a very significant correlation between the elimination of sodium in a 24 h urine (mEq/kg/24 h) and the Na-Fractional-Excretion (EFNa): r = 0.8 (P < .001). There was a correlation between the potassium elimination in 24h (mEq/kg/24h) and EFK: r = 0.85 (P < .001). Between volume/min/1.73m2 and the urine volume percent of GF was: r = 0.88 (P < .001). CONCLUSIONS: These equations provide valuable information of the state of the basal renal function without having to use a timed urine

[Basal renal function in paediatric patients: correlation of methods that depend on a 24h urine collection with simpler methods that do not require a timed urine]. / Función renal basal en pediatría: correlación de métodos que dependen de la recogida de orina de 24h con otros más sencillos que no requieren orina minutada.

INTRODUCTION: In daily clinical practice a quick, easy and accessible method is needed to adequately assess renal function. The objectives of this study were: 1. To quantify the relationship and concordance of the glomerular filtration rate (GF) calculated by the clearance of creatinine in 24h urine (CCr) and the original and modified Schwartz equation (SE); and 2. To correlate urine elimination of substances that depends on the volume of excreted urine in a unit of time with other parameters that are calculated measuring the concentration of these substances in blood and urine. MATERIAL AND METHODS: The study included 401 healthy children with ages between 3 to 14 years (187 male and 214 female). The analysis between the variables was carried out using Pearson's correlation coefficient and the intraclass correlation coefficient (ICC). RESULTS: The correlation between values of CCr and the original SE (non-standardised creatinine measurement) was r=0.58 (P<0.001) and the concordance, ICC=0.74. The correlation between CCr values and the modified SE (standardised creatinine measurement) was r=0.68 (P<.001), and the concordance ICC=0.78. There was a very significant correlation between the elimination of sodium in a 24h urine (mEq/kg/24h) and the Na-Fractional-Excretion (EFNa): r=0.8 (P<.001). There was a correlation between the potassium elimination in 24h (mEq/kg/24h) and EFK: r=0.85 (P<.001). Between volume/min/1.73m2 and the urine volume percent of GF was: r=0.88 (P<.001). CONCLUSIONS: These equations provide valuable information of the state of the basal renal function without having to use a timed urine.